CentOS 8.2 k8s 基础环境配置

一、基础环境配置

1 IP 修改

机器克隆后 IP 修改，使Xshell连接上

[root@localhost ~]# vi /etc/sysconfig/network-scripts/ifcfg-ens160
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="static" # 配置静态IP，防止修改
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens160"
UUID="d20c4f2e-c799-46e6-9a7a-0579c1791c27"
DEVICE="ens160"
ONBOOT="yes"
IPADDR="192.168.192.10" # 修改ip地址
PREFIX="24"
GATEWAY="192.168.192.2" # 修改网关地址
IPV6_PRIVACY="no"
DNS1=114.114.114.114 # DSN配置上，不然使用域名会找不到的
DNS2=8.8.8.8

重启网卡，并测试好不好使

[root@localhost software]# nmcli c reload ens160
[root@localhost software]# nmcli c up ens160
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/5)
[root@localhost software]# 重启完后测试
[root@localhost software]# ping 114.114.114.114
PING 114.114.114.114 (114.114.114.114) 56(84) bytes of data.
64 bytes from 114.114.114.114: icmp_seq=1 ttl=128 time=30.8 ms
64 bytes from 114.114.114.114: icmp_seq=2 ttl=128 time=30.6 ms
64 bytes from 114.114.114.114: icmp_seq=3 ttl=128 time=28.10 ms
64 bytes from 114.114.114.114: icmp_seq=4 ttl=128 time=30.1 ms
64 bytes from 114.114.114.114: icmp_seq=5 ttl=128 time=34.4 ms
^C
--- 114.114.114.114 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 14ms
rtt min/avg/max/mdev = 28.999/30.978/34.430/1.841 ms

2 设置主机名

hostnamectl set-hostname kube-master01
hostnamectl set-hostname kube-node01
hostnamectl set-hostname kube-node02
hostnamectl set-hostname kube-vip

3 配置hosts本地解析

cat > /etc/hosts <<EOF
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.192.10 kube-master01
192.168.192.20 kube-node01
192.168.192.30 kube-node02
192.168.192.40 kube-vip
EOF

4 关闭防火墙 / Selinux / Swap

为了避免额外的干扰，需要关闭防火墙，对于公有云，内网端口一般全开放，外网端口通过安全组控制

# 关闭防火墙
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# systemctl disable firewalld
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.

# 关闭Selinux
# 永久关闭
[root@localhost ~]# sed -i "s#^SELINUX=.*#SELINUX=disabled#g" /etc/selinux/config
# 临时关闭
[root@localhost ~]# setenforce 0
# 检查
[root@localhost ~]# /usr/sbin/sestatus -v
SELinux status:                 enabled

# 先查看 Swap有没有
[root@localhost ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:           1800        1208         122          15         469         417
Swap:          2047          15        2032
# 关闭 Swap 分区，Swap 会影响性能
[root@localhost ~]# swapoff -a && sysctl -w vm.swappiness=0
vm.swappiness = 0
[root@localhost ~]# sed -ri '/^[^#]*swap/s@^@#@' /etc/fstab
# 在确认下 [查看swap一行全是0就正确]
[root@localhost ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:           1800        1210         110          25         479         406
Swap:             0           0           0
[root@localhost ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
# 主机名解析
[root@localhost ~]# echo "127.0.0.1 $(hostname)" >> /etc/hosts
[root@localhost ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
127.0.0.1 localhost.localdomain

5 YUM 源配置

本地或者自建服务器都需要配置 YUM 源，如果是云服务器由于本身就有对应云的 YUM 源，不需要配置

# 备份旧的 yum 源
cd /etc/yum.repos.d/
mkdir backup-$(date +%F)
mv *repo backup-$(date +%F)

# 上面看不懂，这有简单的
[root@localhost yum.repos.d]# mkdir /etc/yum.repos.d.bak
[root@localhost yum.repos.d]# cp /etc/yum.repos.d/* /etc/yum.repos.d.bak/
[root@localhost yum.repos.d]# ls /etc/yum.repos.d.bak/

# 添加阿里云 yum 源
[root@localhost yum.repos.d]# curl http://mirrors.aliyun.com/repo/Centos-7.repo -o ali.repo
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  2523  100  2523    0     0  13637      0 --:--:-- --:--:-- --:--:-- 13637

6 基础依赖安装

由于服务器最小化安装，需要安装一些常用的依赖和工具，否则后面安装可能会报错

# 安装 epel 源
[root@localhost yum.repos.d]# yum -y install epel-release
[root@localhost yum.repos.d]# yum clean all
33 files removed
[root@localhost yum.repos.d]# yum makecache

# 安装常用依赖
yum -y install gcc glibc gcc-c++ make cmake net-tools screen vim lrzsz tree dos2unix lsof \
    tcpdump bash-completion wget openssl openssl-devel bind-utils traceroute \
    bash-completion glib2 glib2-devel unzip bzip2 bzip2-devel libevent libevent-devel \
    expect pcre pcre-devel zlib zlib-devel jq psmisc tcping yum-utils device-mapper-persistent-data \
    lvm2 git device-mapper-persistent-data bridge-utils container-selinux binutils-devel \
    ncurses ncurses-devel elfutils-libelf-devel ack

# 升级服务器
yum -y update

注意：yum 安装出错，看最后一个报错标题里面找。

7 配置时间同步

本地或者自建服务器都需要配置时间同步，如果是云服务器由于本身就有对应云的时间同步机制，不需要配置

echo "# 互联网时间同步" >> /var/spool/cron/root
echo "*/5 * * * * /usr/sbin/ntpdate time2.aliyun.com >/dev/null 2>&1" >> /var/spool/cron/root

8 互相免密

Master 节点执行以下操作

ssh-keygen -t rsa

# 定义 master 列表
MASTER_LIST=(
192.168.192.10
192.168.192.30
)

# 配置免密登录
for i in ${MASTER_LIST[@]};do
    ssh-copy-id -i /root/.ssh/id_rsa.pub root@$i
done

# yes
# 输入密码

9内核升级

在 Kubernetes 的 Github 仓库中：

• https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.25.md

有提到关于内核版本的问题：

• Faster mount detection for linux kernel 5.10+ using openat2 speeding up pod churn rates. On Kernel versions less 5.10, it will fallback to using the original way of detecting mount points i.e by parsing /proc/mounts.
• 这意味着内核 5.10 版本以后会使用 openat2 进行更快的挂载检测，所有可以将内核升级到 5.10 以后，但没必要最新。
• 这里使用的是 5.11.16 版本，更新于 2021 年 4 月。如果想安装其它版本可以去下面网站下载：http://193.49.22.109/elrepo/kernel/el7/x86_64/RPMS/

创建用于存放安装包并下载

mkdir -p /opt/software/kernel
cd /opt/software/kernel
wget http://193.49.22.109/elrepo/kernel/el7/x86_64/RPMS/kernel-ml-5.11.14-1.el7.elrepo.x86_64.rpm
wget http://193.49.22.109/elrepo/kernel/el7/x86_64/RPMS/kernel-ml-devel-5.11.14-1.el7.elrepo.x86_64.rpm

执行安装

yum localinstall -y kernel-ml*

# 设置内核启动顺序
grub2-set-default  0 && grub2-mkconfig -o /etc/grub2.cfg

# 查看默认内核
grubby --default-kernel

注意：CentOS 8.2 对以上内核升级需要安装各种依赖。

CentOS 7.9 升级内核 kernel-ml-5.6.14版本：https://www.jb51.net/article/265146.htm

Centos 8.2 升级内核通过elrepo源：https://www.jb51.net/article/265151.htm

10 系统优化

对系统打开文件数进行修改，提升性能

cat >> /etc/security/limits.conf << EOF
# 打开文件优化配置
* soft nofile 655360
* hard nofile 655350
* soft nproc 655350
* hard nproc 655350
* soft memlock unlimited
* hard memlock unlimited
EOF

cat /etc/security/limits.conf

11 加载模块

ipvs模块配置

kube-proxy开启ipvs的前置条件

• 原文：https://github.com/kubernetes/kubernetes/blob/master/pkg/proxy/ipvs/README.md
• 参考：https://www.qikqiak.com/post/how-to-use-ipvs-in-kubernetes/

创建配置文件

内核 4.19+版本 nf_conntrack_ipv4 已改为 nf_conntrack ，4.18以下使用 nf_conntrack_ipv4即可。

安装 ipvsadm，节点通信需要用到 LVS，所有需要安装 ipvsadm。ipset 和 ipvsadm (便于查看 ipvs 的代理规则)

yum -y install ipvsadm ipset sysstat conntrack libseccomp

配置 ipvs 模块（内核 4.19 版本以前使用 nf_conntrack_ipv4，以后使用 nf_conntrack）

modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack

cat > /etc/modules-load.d/ipvs.conf << EOF
ip_vs
ip_vs_lc
ip_vs_wlc
ip_vs_rr
ip_vs_wrr
ip_vs_lblc
ip_vs_lblcr
ip_vs_dh
ip_vs_sh
ip_vs_fo
ip_vs_nq
ip_vs_sed
ip_vs_ftp
ip_vs_sh
nf_conntrack
ip_tables
ip_set
xt_set
ipt_set
ipt_rpfilter
ipt_REJECT
ipip
EOF

重新加载配置

# 加载内核配置 警告忽略
systemctl enable --now systemd-modules-load.service

检查确认

[root@localhost etc]# lsmod | grep --color=auto -e ip_vs -e nf_conntrack
ip_vs_ftp              16384  0
ip_vs_sed              16384  0
ip_vs_nq               16384  0
ip_vs_fo               16384  0
ip_vs_dh               16384  0
ip_vs_lblcr            16384  0
ip_vs_lblc             16384  0
ip_vs_wlc              16384  0
ip_vs_lc               16384  0
ip_vs_sh               16384  0
ip_vs_wrr              16384  0
ip_vs_rr               16384  0
ip_vs                 176128  24 ip_vs_wlc,ip_vs_rr,ip_vs_dh,ip_vs_lblcr,ip_vs_sh,ip_vs_fo,ip_vs_nq,ip_vs_lblc,ip_vs_wrr,ip_vs_lc,ip_vs_sed,ip_vs_ftp
nf_conntrack_tftp      20480  3 nf_nat_tftp
nf_nat                 49152  4 nf_nat_tftp,nft_chain_nat,xt_MASQUERADE,ip_vs_ftp
nf_conntrack          159744  7 xt_conntrack,nf_nat,nf_conntrack_tftp,nft_ct,nf_nat_tftp,xt_MASQUERADE,ip_vs
nf_defrag_ipv6         24576  2 nf_conntrack,ip_vs
nf_defrag_ipv4         16384  1 nf_conntrack
libcrc32c              16384  4 nf_conntrack,nf_nat,xfs,ip_vs

# 或者

[root@localhost etc]# cut -f1 -d " "  /proc/modules | grep -e ip_vs -e nf_conntrack
ip_vs_ftp
ip_vs_sed
ip_vs_nq
ip_vs_fo
ip_vs_dh
ip_vs_lblcr
ip_vs_lblc
ip_vs_wlc
ip_vs_lc
ip_vs_sh
ip_vs_wrr
ip_vs_rr
ip_vs
nf_conntrack_tftp
nf_conntrack

12 优化系统参数

添加内核调优参数，某些参数对 Kubernetes 集群很重要(不一定是最优，各取所有)

cat >> /etc/sysctl.d/user.conf << EOF
# 内核调优
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
fs.may_detach_mounts = 1
vm.overcommit_memory=1
vm.panic_on_oom=0
fs.inotify.max_user_watches=89100
fs.file-max=52706963
fs.nr_open=52706963
net.netfilter.nf_conntrack_max=2310720
net.ipv4.tcp_keepalive_time = 600
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_keepalive_intvl =15
net.ipv4.tcp_max_tw_buckets = 36000
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_max_orphans = 327680
net.ipv4.tcp_orphan_retries = 3
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_max_syn_backlog = 16384
net.ipv4.ip_conntrack_max = 65536
net.ipv4.tcp_timestamps = 0
net.core.somaxconn = 16384
EOF

两种方式

1 单独指定配置文件加载

sysctl -p /etc/sysctl.d/user.conf

2 手动加载所有的配置文件

[root@localhost etc]# sysctl --system
* Applying /usr/lib/sysctl.d/10-default-yama-scope.conf ...
kernel.yama.ptrace_scope = 0
* Applying /usr/lib/sysctl.d/50-coredump.conf ...
kernel.core_pattern = |/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h %e
* Applying /usr/lib/sysctl.d/50-default.conf ...
kernel.sysrq = 16
kernel.core_uses_pid = 1
kernel.kptr_restrict = 1
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.all.promote_secondaries = 1
net.core.default_qdisc = fq_codel
fs.protected_hardlinks = 1
fs.protected_symlinks = 1
* Applying /usr/lib/sysctl.d/50-libkcapi-optmem_max.conf ...
net.core.optmem_max = 81920
* Applying /usr/lib/sysctl.d/50-pid-max.conf ...
kernel.pid_max = 4194304
* Applying /usr/lib/sysctl.d/60-libvirtd.conf ...
fs.aio-max-nr = 1048576
* Applying /etc/sysctl.d/99-sysctl.conf ...
* Applying /etc/sysctl.d/user.conf ...
net.ipv4.ip_forward = 1
vm.overcommit_memory = 1
vm.panic_on_oom = 0
fs.inotify.max_user_watches = 89100
fs.file-max = 52706963
fs.nr_open = 52706963
net.netfilter.nf_conntrack_max = 2310720
net.ipv4.tcp_keepalive_time = 600
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_keepalive_intvl = 15
net.ipv4.tcp_max_tw_buckets = 36000
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_max_orphans = 327680
net.ipv4.tcp_orphan_retries = 3
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_max_syn_backlog = 16384
net.ipv4.tcp_timestamps = 0
net.core.somaxconn = 16384
* Applying /etc/sysctl.conf ...

完成后就可以重启服务器

reboot

重启完成，在查看 ipvs 的配置效果

lsmod | grep --color=auto -e ip_vs -e nf_conntrack

二、报错

1 域名解析不了

ping: baidu.com: Name or service not known

0curl: (6) Could not resolve host: mirrors.aliyun.com

解决

[root@localhost ~]# vi /etc/sysconfig/network-scripts/ifcfg-ens160
...
GATEWAY="192.168.192.2" # 修改网关地址
IPV6_PRIVACY="no"
# 域名解析，网关也要对
DNS1=114.114.114.114
DNS2=8.8.8.8

重启

[root@localhost software]# nmcli c reload ens160
[root@localhost software]# nmcli c up ens160
[root@localhost yum.repos.d]# ping baidu.com
PING baidu.com (110.242.68.66) 56(84) bytes of data.
64 bytes from 110.242.68.66 (110.242.68.66): icmp_seq=1 ttl=128 time=24.0 ms
64 bytes from 110.242.68.66 (110.242.68.66): icmp_seq=2 ttl=128 time=26.5 ms
^C
--- baidu.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 4ms
rtt min/avg/max/mdev = 24.005/25.233/26.462/1.238 ms

2 yum 安装出错

[root@localhost yum.repos.d]# yum -y install epel-release
CentOS-8 - AppStream                                                                                       81  B/s |  38  B     00:00
Error: Failed to download metadata for repo 'AppStream': Cannot prepare internal mirrorlist: No URLs in mirrorlist

解决

如果仍然需要运行旧CentOS 8，可以在/etc/yum.repos中更新repos.d使用vault.centos.org代替mirror.centos.org

修改下面两个文件

cd /etc/yum.repos.d
vi CentOS-Base.repo
vi CentOS-AppStream.repo

CentOS-BaseOS.repo的内容修改为

[baseos]
name=CentOS Linux $releasever - BaseOS
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=BaseOS&infra=$infra
#baseurl=http://mirror.centos.org/$contentdir/$releasever/BaseOS/$basearch/os/
baseurl=https://vault.centos.org/centos/$releasever/BaseOS/$basearch/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

CentOS-AppStream.repo的内容修改为

[appstream]
name=CentOS Linux $releasever - AppStream
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=AppStream&infra=$infra
#baseurl=http://mirror.centos.org/$contentdir/$releasever/AppStream/$basearch/os/
baseurl=https://vault.centos.org/centos/$releasever/AppStream/$basearch/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

再执行yum -y install epel-release命令，发现成功了！

三、安装 k8s

centos系统安装Kubernetes集群步骤： https://www.jb51.net/article/233987.htm

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